Ribbon bonding for device interconnection
Ribbon bonding has potential for the interconnection of high lead count, small pad size (less than 50 micrometre) devices (especially for small batch production). It combines the flexibility of wire bonding with the mechanical and electrical characteristics and fine feature sizes of lead frames.Future applications may include the interconnection of high lead count, small feature size VLSI devices, and the intra- and inter-connection of high speed, high frequency microwave type devices.
Ribbon bonding may offer an alternative to TAB and should be attractive since many conventional wire bonding equipments can be easily adapted to handle ribbons. The process achieves the required density of interconnections for both inner and outer bonds. At the same time it eliminates the need for either bumped chips or tape, and it avoids the tooling costs normally associated with TAB.
To summarise, ribbon bonding has great potential in the manufacture of devices with small bond pads and/or high density interconnections.
Ribbon bonding investigations carried out at TWI include the ultrasonic bonding of:
- gold ribbon (30x8 micrometres) to aluminium thin film on silicon
- copper ribbon (30x8 micrometres) to copper tracks printed circuit boards
- aluminium 1% silicon ribbon (30x12 micrometres) to copper tracks on alumina substrates